A solo homer by Pirates outfielder Brandon Moss back in the second had staked the Pirates to an early one-run lead against Cain, who was seeking to become just the third NL pitcher to reach the 11-win mark this season. Meanwhile, Duke cruised, with only four Giants hitters reaching base through five innings.
And then, in a frenzied and quick attack by the Giants offense, it all unraveled.
"I just left some pitches up and they made me pay for it," Duke said afterward. "The Giants attack first pitches very well, and you have to make quality pitches from the first pitch of the at-bat."
It began with a leadoff double by Giants outfielder Randy Winn on a ball that Pirates center fielder Andrew McCutchen nearly made a diving catch on. Pablo Sandoval then sent a first-pitch curveball into the left-center-field gap for an RBI double. Bengie Molina connected on a first-pitch fastball for an RBI double. And Nate Schierholtz put together a patient seven-pitch at-bat that, yes, resulted in an RBI double.
The four consecutive doubles would ultimately cost Duke four runs, as the Giants subsequently enjoyed their first lead of the series.
"They jumped on the first pitch," manager John Russell said. "He left some balls up and they took advantage of it. Unfortunately, that was the inning that really hurt us."
With little in the way of success against Cain, that would indeed be enough to snap the Pirates' five-game home winning streak against the Giants. Pittsburgh came in having won 18 of the last 23 contests between the two clubs.
"Aside from that inning, I felt like I did pretty well," said Duke, now 0-4 in his last four starts. "I kept the ball down. I pitched my game other than that inning. I guess with a guy throwing like Cain was today, that's the difference in the game."
Duke finished seven innings in all, but left trailing by three. He didn't allow another hit after that fourth sixth-inning double, but yet again, he didn't benefit from much run support. The Pirates have now scored just nine runs when Duke has been on the mound in his nine losses.
"This whole series was about our pitchers," Adam LaRoche said. "We could have gotten swept just as easily as we won two without excellent starting pitching. That's been the story of the year -- those guys keeping us in games. We need to start stepping up and scoring some more runs for them."
Against Cain, the Pirates made little headway. Aside from Moss' homer, the Giants right-hander limited the Pirates to just four hits in his seven innings.
"He's one of our horses," said Giants manager Bruce Bochy, whose team boasts a Major Legaue-best 3.46 ERA. "I think he's emerged as one of the better young pitchers in the game."
A fourth-inning opportunity gone for naught against Cain did loom largely, though. The Pirates seemed poised to extend what was then a one-run lead, but ran themselves out of an opportunity to do so when Ryan Doumit was thrown out trying to stretch a one-out single into a two-base hit. LaRoche followed with a double that might have scored Doumit had he not been thrown out trying to advance.
The Pirates would make some noise later as well, and this time they capitalized to at least make things interesting. With Cain out of the game, Doumit delivered a two-run single to plate McCutchen and Freddy Sanchez and bring Pittsburgh within one.
LaRoche, who had broken an 0-for-22 streak two at-bats prior, followed and watched three straight balls go by from reliever Jeremy Affeldt. He then saw a 3-0 fastball that he liked and went after it. The result: an inning-ending double play that enlisted boos from the crowd.
"It was where I was looking and like the last three weeks, I'm just not getting good swings on it," said LaRoche, who has just five hits this month. "I was looking for something to drive, and sure enough, double play. Frustrating."
Said Affeldt: "I just tried to kind of keep it in and off on his hands, where I could maybe try to keep it off his barrel. It just happened to work out."
After relievers Donnie Veal and Evan Meek combined to pitch a scoreless ninth, the Pirates did put the tying run on first with one out in the bottom half of the frame. But Andy LaRoche would never advance, as Ramon Vazquez popped out and Delwyn Young struck out to end the game.
"They have some tremendous arms, not only in their rotation but in their bullpen," Russell said. "When you get down three runs, it's tough to come back on a team like that. We had some chances, but it's tough against a team like that."
Shortstop Jack Wilson had to come out of the game for a pinch-hitter in the ninth after his left knee tightened up. Wilson had been struck on the knee in the eighth on a line drive. The injury is not expected to be anything serious.